用竖式计算 20-11= 30-22= 36-28= 37-18= 30-26= 21-13= 21-6= 40-28=
21-19= 40-37= 31-18=
20-13= 20-15= 20-17= 21-2= 21-14=
1
21-17= 22-13= 22-15=
22-17= 41-34= 41-28= 33-7= 33-14=
22-18= 23-14= 23-16= 23-19= 24-15= 24-17= 32-16= 34-28=
24-18= 33-26= 42-36= 24-19= 25-16= 26-17= 27-18= 28-19=
2
20-12= 20-26= 30-24= 30-28= 20-19= 21-15= 31-23= 40-36=
31-26= 35-28=
30-21= 30-13= 30-5= 30-19= 31-22= 31-15=
31-29= 32-13=
32-14= 32-25= 22-14= 41-6= 23-17= 34-27=
3
26-19= 32-17= 24-16= 25-17= 42-8= 26-18= 32-8= 32-29=